1. Field of the Invention
Embodiments of the present invention generally relate to an apparatus for reinforcing the backing plate on a plasma enhanced chemical vapor deposition (PECVD) apparatus.
2. Description of the Related Art
Large area substrates may be used for the fabrication of numerous items used in society such as flat panel displays and solar cell panels. A large area substrate may exceed 2 square meters in surface area. To process these large area substrates, chamber size may also increase. One suitable apparatus that may be used to process large area substrates is a PECVD apparatus 700 as shown in FIG. 7. A substrate 704 is disposed in the processing chamber opposite to a gas distribution showerhead 702. A backing plate 706 is disposed behind the showerhead 702 to create a plenum 708 between the showerhead 702 and the backing plate 706 for distribution of processing gas behind the showerhead 702. For a PECVD chamber, the backing plate 706 may be at least as large as the large area substrate 704. Hence, in a PECVD apparatus for processing large area substrates, the backing plate may exceed 2 square meters in surface area. By simply scaling up a processing chamber and increasing its surface area, the size and weight of the backing plate may eventually result in the center of the backing plate 706 sagging as shown in FIG. 7 when the backing plate 706 retains the thickness of the smaller chambers. Therefore, there is a need in the art for a backing plate of sufficient size and mechanical strength to permit processing of large area substrates.